Ultra-wideband technology brings the convenience and mobility of wireless communications to high-speed interconnects in devices throughout the digital home and office. Designed for low-power, short-range, wireless personal area networks (WPANs), UWB is the leading technology for freeing people from wires, enabling wireless connection of multiple devices for transmission of video, audio and other high-bandwidth data.
Nowadays, one of major key technology of UWB system is to design a compact, wideband and omni-directional antenna. During these ten years, planer monopole antennas are used as wide band antennas. However, two-dimensional 3GHz~5GHz UWB antennas are seldom investigated in the literatures. In this research, we propose a whole planer 3GHz~5GHz UWB antenna and employ both slit and parasitic methods to increase the bandwidth of the antenna with miniature characteristic.
Two techniques are proposed to miniature compact design of the planar UWB monopole antennas and increase antenna bandwidth. One technique is to design the slit shape on the monopole radiator to miniature antenna. Antenna reactance can be changed by this slit shape structure instead of increasing the gap size between monopole radiator and ground plane which increases the antenna dimensions. By these two techniques, the antenna size can be reduced about 33％.
To reduce manufacture cost and practical fabrication, we also propose a simplified antenna structure. Wideband characteristics of the simplified structure antenna are similar to that of semi-circular structure. Moreover, we also try to find the minimum size of the antenna. Wide band characteristics are defect when the dimension of the antenna is further reduced by decreasing ground length. However, slit structure method is employed to improve antenna wideband characteristic.
Finally the antenna prototypes are fabricated and the antenna characteristics are measured. The antenna characteristics measured includes the S parameter and radiation patterns. The consistency between the simulated results and the measurement results confirm the practicability of these techniques.